23–28 Aug 2026
America/Los_Angeles timezone

Reverse undulator tapering for polarization control and short pulse generation

TUX01
25 Aug 2026, 08:30
20m
Invited Oral Presentation Session 4: SASE FEL SASE FEL (Invited)

Speaker

Evgeny Schneidmiller (Deutsches Elektronen-Synchrotron DESY)

Description

Reverse undulator taper is a unique method allowing to strongly suppress radiation intensity at the exit of SASE undulator while maintaining microbunching at a significant level. Recently, it was used to generate high-purity circularly polarized radiation from dedicated afterburners (Apple-X at the European XFEL and Apple-III at FLASH, the latter operates at the 3rd harmonic of SASE undulator). Chirp-taper compensation is another method where a reverse taper is typically used to generate attosecond pulses in X-ray FELs. Recent results from the European XFEL on generation of extremely short (~ 100 as) and intense (~ 10 TW) pulses in soft X-ray regime are presented. Finally, so-called excessive reverse taper (beyond the compensation condition) helps to generate short pulses well below cooperation length limit. The validity of the concept is illustrated by the experimental results from FLASH.

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Author

Evgeny Schneidmiller (Deutsches Elektronen-Synchrotron DESY)

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